Corefix in a Garage Conversion Project

Fixing heavy items to a “dot and dab” wall (plasterboard attached over blockwork with adhesive, with a cavity in between) can be a challenge, as the plasterboard is largely unsupported and may not be strong enough to hold the load on its own. Fixing to the blockwork through the plasterboard with e.g. regular frame fixings also risks severely distorting or crushing the plasterboard into the cavity behind it. Failed fixings are the last thing anyone wants when hanging up something expensive!  

James Eades, MD of Systemagic in Wiltshire, was recently faced with this challenge when decorating his new garage conversion. The garage had a bedroom built above it, with the double garage itself converted into a single garage and an office space. He planned to put up a wall TV, as well as hang up his valuable and much-loved guitar collection, which meant that the installation had to be 100% secure to avoid an expensive disaster. 

“The hangers needed to be secure and give me the confidence that nothing will happen! I would have used standard wall plugs, but I didn’t have confidence that they wouldn’t pull out of the plasterboard over time”, James explains.   

What is Corefix? 

James researched dot & dab wall fixings on Google and came across Corefix, which he’d never used before: “With standard plugs I’ve had a good experience on stud walls, but very poor experience on dot & dab walls.  Over time the plug starts to pull out and pull the plaster where it’s only secured by a thin bit of plasterboard. Knowing I was hanging expensive items, I decided to research and came across Corefix, which addressed the exact concern I was having”, he describes.   

Corefix is a unique heavy duty fixing designed specifically for dot & dab walls, although it works just as well in masonry. Because of the gap between plasterboard and blockwork, the problem with fixing heavy loads to dot & dab walls is either having to rely on the plasterboard alone, or risking the plasterboard bowing or crushing into the gap. Corefix resolves the issue with an engineered steel core, which bridges the gap, taking the pressure off the plasterboard so the load is supported by the masonry behind it instead.  

Hanging it all up

Corefix is installed by drilling a 100mm deep hole into the dot & dab wall with a 10mm drill bit, inserting the plug, tapping in the steel core and tightening the screw. When using with lightweight aircrete blocks that easily crumble, we recommend drilling a 6mm pilot hole in the first instance.  

James installed 6 hooks for his guitars, tested the installation afterwards, and found the whole process very easy, although drilling into the solid concrete wall of the garage took longer than expected: “The instructions were very easy to follow – we hung 6 guitars in 90 minutes with 12 fixings in total. It would have been quicker, but the wall was concrete block rather than breeze block, so even my brand new masonry drill bit took a lot of effort to drill the holes.” 

Hanging up wall TVs

James also used another 4 Corefix fixings to attach the bracket for his wall-mounted TV and found the process quick and easy: “I decided to ignore the fixings that came with the TV mount and use Corefix instead.  It took about 5 minutes start to finish to put it up, it’s really secure and I’ve got the confidence that it’s properly anchored to the block.” Drilling was also easier and faster for mounting the TV, as the wall was lightweight thermalite block instead of concrete.  

Corefix is ideal for wall mounted TVs, as it transfers the load into the blockwork meaning your TV won’t need to hang on by the strength of the plasterboard alone. It’s always a good idea to use at least 4 fixings for a TV bracket, but a normal bracket like James was using will be very secure on a dot & dab or masonry wall with Corefix.   

However, if you’re attaching a cantilever bracket (i.e. a TV that swings out from the wall), the force affecting the fixings will be much greater, and you’ll need to take this into account. When the weight is close to the wall, the main force affecting the installation is the shear force, which pulls straight down as shown in the diagram.  

With cantilever brackets, as the weight of the TV moves further away from the wall, the tension force (which pulls outwards) increases and begins pulling on the fixings more and more – this is why you should always test the security of the fixing before mounting a heavy TV with a cantilever bracket, regardless of what your wall is made of and what fixings you’re using. Overall, we would recommend you check with our technical department before installing any cantilever TV mounts – contact us HERE.

Installation tips

From his experience, James recommends using a new and sharp masonry drill bit to ensure a clear and clean hole, especially if you’re drilling into solid concrete block rather than breeze block or aerated concrete. Breeze blocks and aerated concrete are more lightweight and usually contain ash or other aggregates in addition to concrete, which makes them easier to work with on site and drill into but less dense.  

Drilling into concrete block with a regular rotary drill is doable, but you still need to do it carefully as it can otherwise damage your drill bit or burn out the motor. If you’re drilling into old concrete, which is likely to be much denser, it’s a good idea to buy or rent a hammer drill instead.

James also recommended using a smaller 9mm drill bit for a tighter fit, instead of the instructed 10mm (although both will work) and tapping the plug halfway in before inserting the steel core to give the plug structure to hammer in the last bit.

You can find Corefix in B&Q, Tradepoint, Screwfix and other stockists. 

Find datasheets, videos and more info in our Fixings Knowledge Base!

If you have questions about fixings, we’re here to help – get in touch by email or call 0800 130 3646.